Archive for the ‘materials’ category: Page 117

Jan 31, 2020

Researchers find evidence for metallic hydrogen at 425 gigapascals

Posted by in categories: materials, mathematics

A team of researchers, two with the French Atomic Energy Commission (AEC) and a third with the Soleil synchrotron, have found evidence of a phase change for hydrogen at a pressure of 425 gigapascals. In their paper published in the journal Nature, Paul Loubeyre, Florent Occelli and Paul Dumas describe testing hydrogen at such a high pressure and what they learned from it.

Researchers long ago theorized that if gas were exposed to enough pressure, it would transition into a metal. But the theories were not able to derive how much pressure is required. Doubts about the theories began to arise when scientists developed tools capable of exerting the high pressures that were believed necessary to squeeze hydrogen into a metal. Theorists simply moved the number higher.

In the past several years, however, theorists have come to a consensus—their math showed that hydrogen should transition at approximately 425 gigapascals—but a way to generate that much pressure did not exist. Then, last year, a team at the AEC improved on the diamond anvil cell, which for years has been used to create intense pressure in experiments. In a diamond anvil cell, two opposing diamonds are used to compress a sample between highly polished tips—the pressure generated is typically measured using a reference material. With the new design, called a toroidal diamond anvil cell, the tip was made into a donut shape with a grooved dome. When in use, the dome deforms but does not break at high pressures. With the new design, the researchers were able to exert pressures up to 600 GPa. That still left the problem of how to test a sample of hydrogen as it was being squeezed.

Jan 30, 2020

Stress test reveals graphene won’t crack under pressure

Posted by in categories: engineering, materials

Graphene is a paradox. It is the thinnest material known to science, yet also one of the strongest. Now, research from University of Toronto Engineering shows that graphene is also highly resistant to fatigue—able to withstand more than a billion cycles of high stress before it breaks.

Jan 29, 2020

‘Curious and curiouser!’ Meteorite chunk contains unexpected evidence of presolar grains

Posted by in categories: materials, space travel

An unusual chunk in a meteorite may contain a surprising bit of space history, based on new research from Washington University in St. Louis.

Presolar —tiny bits of solid interstellar material formed before the sun was born—are sometimes found in primitive meteorites. But a new analysis reveals evidence of presolar grains in part of a where they are not expected to be found.

“What is surprising is the fact that presolar grains are present,” said Olga Pravdivtseva, research associate professor of physics in Arts & Sciences and lead author of a new paper in Nature Astronomy. “Following our current understanding of solar system formation, presolar grains could not survive in the environment where these inclusions are formed.”

Jan 28, 2020

Astronomers Have Caught a Rare And Massive ‘Accretion Burst’ in Our Galaxy

Posted by in categories: cosmology, materials

Here on Earth, we pay quite a lot of attention to the sun. It’s visible to us, after all, and central to our lives. But it is only one of the billions of stars in our galaxy, the Milky Way. It’s also quite small compared to other stars – most are at least eight times more massive.

These massive stars influence the structure, shape and chemical content of a galaxy. And when they have exhausted their hydrogen gas fuel and die, they do so in an explosive event called a supernova. This explosion is sometimes so strong that it triggers the formation of new stars out of materials in the dead star’s surroundings.

But there’s an important gap in our knowledge: astronomers don’t yet fully understand how those original massive stars themselves are initially formed. So far, observations have only yielded some pieces of the puzzle.

Jan 28, 2020

Method detects defects in 2-D materials for future electronics, sensors

Posted by in categories: materials, particle physics

To further shrink electronic devices and to lower energy consumption, the semiconductor industry is interested in using 2-D materials, but manufacturers need a quick and accurate method for detecting defects in these materials to determine if the material is suitable for device manufacture. Now a team of researchers has developed a technique to quickly and sensitively characterize defects in 2-D materials.

Two-dimensional materials are atomically thin, the most well-known being graphene, a single-atom-thick layer of carbon atoms.

“People have struggled to make these 2-D materials without defects,” said Mauricio Terrones, Verne M. Willaman Professor of Physics, Penn State. “That’s the ultimate goal. We want to have a 2-D material on a four-inch wafer with at least an acceptable number of defects, but you want to evaluate it in a quick way.”

Jan 27, 2020

These DARPA-funded bricks can self-repair—and replicate

Posted by in category: materials

While not as strong as concrete, the bricks could reduce the CO2 footprint of a building, self-heal, and even reproduce.

[Photo: University of Colorado Boulder College of Engineering and Applied Science].

Jan 27, 2020

Building High-Rises Out of Wood Can Help Save the Planet

Posted by in category: materials

Concrete and steel come with massive emissions. So let’s ditch them and build towers out of wood. Yes, wood.

Jan 25, 2020

Better interior design might keep astronauts healthier and happier in deep space

Posted by in categories: materials, space travel

When it comes to building the interior of a spacecraft, engineers often prioritize function over aesthetics, focusing on materials and hardware that are both safe and effective for executing the vehicle’s intended mission. But some scientists say it’s time to consider another crucial factor when designing a spacecraft’s insides: how it will affect the behavior of the passengers?

Jan 24, 2020

Philippine city makes bricks from Taal Volcano ash for reconstruction work

Posted by in category: materials

A Philippine city affected by heavy ashfall from the nearby Taal Volcano has started collecting ash to make bricks, providing needed building materials for post-disaster reconstruction in neighbouring towns.

Continue reading “Philippine city makes bricks from Taal Volcano ash for reconstruction work” »

Jan 24, 2020

Transparent material conducts and insulates heat at the same time

Posted by in categories: computing, materials

Different kinds of materials can play different roles when it comes to controlling heat. If we want to keep our home warm in the depths of winter, insulating layers in our walls can help to lock it in. If we want to keep things cool, thermally conductive materials like those used in computer processors can help carry it away. But could one material have it both ways? A new breakthrough suggests that it could, made by a team of scientists who believe heat needn’t just be a one way street.

The research was carried out by scientists at the University of Bayreuth and the Max Planck Institute for Polymer Research, who sought to combine the thermally insulating properties of materials like polystyrene, with the thermally conductive properties of heavy metals often used to dissipate heat.

Their breakthrough boils down to a way of manipulating the way heat travels, which is through the oscillation of individual molecules that pass on their movement to neighboring molecules.